Added texture cache and sprite origins.

AlientAttack.MonoGame/Things/Enemies/EnemyShip.cs

@@ -1,13 +1,19 @@
 using AlienAttack.MonoGame.Things.Bullets;
+using Microsoft.Xna.Framework;
 
 namespace AlienAttack.MonoGame.Things.Enemies;
 
-public abstract class EnemyShip(int x, int y) : MoveableSprite(x, y)
+public abstract class EnemyShip : MoveableSprite
 {
     protected abstract int Health { get; set; }
 
     public virtual int CrashDamage => 10;
 
+    public EnemyShip(int x, int y) : base(x, y)
+    {
+        Origin = new(32, 32);
+    }
+
     public override sealed void Update(SpriteUpdateContext context)
     {
         if (Health <= 0)
@@ -22,7 +28,7 @@ public abstract class EnemyShip(int x, int y) : MoveableSprite(x, y)
 
         TryMove(context);
 
-        if (YPosition > context.ViewTransform.ScreenHeight)
+        if (YPosition - Origin.Y > context.ViewTransform.ScreenHeight)
         {
             IsDead = true;
             return;